增
import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;/** * account表 添加一条记录 insert 语句 */public class JDBCDemo { public static void main(String[] args) { Statement stmt = null; Connection conn = null; try { //1. 注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2. 定义sql String sql = "insert into account values(null,'王五',3000)"; //3.获取Connection对象 conn = DriverManager.getConnection("jdbc:mysql:///db", "root", "root"); //4.获取执行sql的对象 Statement stmt = conn.createStatement(); //5.执行sql int count = stmt.executeUpdate(sql);//影响的行数 //6.处理结果 System.out.println(count); if(count > 0){ System.out.println("添加成功！"); }else{ System.out.println("添加失败！"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); }finally { //stmt.close(); //7. 释放资源 //避免空指针异常 if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }}
改
import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;/** * account表 修改记录 */public class JDBCDemo { public static void main(String[] args) { Connection conn = null; Statement stmt = null; try { //1. 注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2.获取连接对象 conn = DriverManager.getConnection("jdbc:mysql:///db", "root", "root"); //3.定义sql String sql = "update account set balance = 1500 where id = 3"; //4.获取执行sql对象 stmt = conn.createStatement(); //5.执行sql int count = stmt.executeUpdate(sql); //6.处理结果 System.out.println(count); if(count > 0){ System.out.println("修改成功！"); }else{ System.out.println("修改失败"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { //7.释放资源 if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }}
删
import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;/** * account表 删除一条记录 */public class JDBCDemo { public static void main(String[] args) { Connection conn = null; Statement stmt = null; try { //1. 注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2.获取连接对象 conn = DriverManager.getConnection("jdbc:mysql:///db3", "root", "root"); //conn = JDBCUtils.getConnection("jdbc:mysql:///db3", "root", "root"); //3.定义sql String sql = "delete from account where id = 3"; //4.获取执行sql对象 stmt = conn.createStatement(); //5.执行sql int count = stmt.executeUpdate(sql); //6.处理结果 System.out.println(count); if(count > 0){ System.out.println("删除成功！"); }else{ System.out.println("删除失败"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { //7.释放资源 if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }}
查
import java.sql.*;import java.util.ArrayList;import java.util.List;/** * 查询所有emp对象 */public class JDBCDemo { public static void main(String[] args) { Connection conn = null; Statement stmt = null; ResultSet rs = null; List<Emp> list = null; try { //1.注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2.获取连接 conn = DriverManager.getConnection("jdbc:mysql:///db3", "root", "root"); //3.定义sql String sql = "select * from emp"; //4.获取执行sql的对象 stmt = conn.createStatement(); //5.执行sql rs = stmt.executeQuery(sql); //6.遍历结果集，封装对象，装载集合 Emp emp = null; list = new ArrayList<Emp>(); while(rs.next()){ //获取数据 int id = rs.getInt("id"); String ename = rs.getString("ename"); int job_id = rs.getInt("job_id"); int mgr = rs.getInt("mgr"); Date joindate = rs.getDate("joindate"); double salary = rs.getDouble("salary"); double bonus = rs.getDouble("bonus"); int dept_id = rs.getInt("dept_id"); // 创建emp对象,并赋值 emp = new Emp(); emp.setId(id); emp.setEname(ename); emp.setJob_id(job_id); emp.setMgr(mgr); emp.setJoindate(joindate); emp.setSalary(salary); emp.setBonus(bonus); emp.setDept_id(dept_id); //装载集合 list.add(emp); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); }finally { if(rs != null){ try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } return list; System.out.println(list); System.out.println(list.size()); }}
创建表
import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;/** * 执行DDL语句 */public class JDBCDemo { public static void main(String[] args) { Connection conn = null; Statement stmt = null; try { //1. 注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2.获取连接对象 conn = DriverManager.getConnection("jdbc:mysql:///db3", "root", "root"); //3.定义sql String sql = "create table student (id int , name varchar(20))"; //4.获取执行sql对象 stmt = conn.createStatement(); //5.执行sql int count = stmt.executeUpdate(sql); //6.处理结果 System.out.println(count); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { //7.释放资源 if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }}
快来打我*
ゞ 浴缸里的玫瑰
亦凉
迷南。
深藏阁楼爱情的钟
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